The problem of increased noise occurs in high-speed transmission systems using laser diodes due to the back light reflected at the junction of optical connectors, that is, at the end surfaces of connected fibers. In order to reduce this reflection at the end surfaces, PC (physical contact) end surface formation technology, in which the ferrule end surface Is processed into a convex rounded surface with the fiber at the center, and in which the end surfaces are tightly connected without airgap when the fibers are connected, has been widely used.
In order to obtain a convex rounded surface, a polishing plate is constructed by gluing a thin polishing sheet onto the upper side of a flat polishing disc made of a soft elastic material. The end surface of the ferrule to be polished is pressed onto this polishing plate while being moved in a circular arc, whereby the polishing disc becomes deflected due to elastic deformation, and using this bending phenomenon, the ferrule and fiber end surfaces are simultaneously formed into a precise convex rounded surface.
On the other hand, because the mechanism for moving the sample and the polishing plate greatly affects both the accuracy of the finish of the end surface and the time required for the polishing, a lapping disc mechanism, which is a well-known device to polish parallel-flat processing objects, is used for the polishing plate. In other words, the ferrule, which is the processing object, is kept stationary while the polishing plate simultaneously revolves and rotates by means of a planetary gear and a drive motor, In this way, the ferrule is placed in contact with the polishing plate and a lapping movement which traces a uniform locus is obtained.
Consequently, the ferrule can be efficiently processed into a desired convex rounded surface with the fiber at the top.
As a conventional example, U.S. Pat. No. 4979334 for an `Optical Fiber End-Face Polishing Device` by M. Takahashi, filed on Dec. 25, 1990, has been disclosed.
As shown in FIG. 6, this device has an eccentric disc 112 which revolves in a concentric circle of a rotating disc, This eccentric disc 112 has a planetary gear assembly 109, 114, 115 which transmits the rotation of a revolution motor, and the planetary gear is connected to the polishing disc 108 so that the polishing disc rotates as well as revolves.
In the above device, because a planetary gear is used for the revolving mechanism even if the revolution motor is stopped, when rotational energy is supplied to the rotational axis, the planetary gear continues to rotate while it engages with the revolution motor, and the polishing disc 118 subsequently ends up revolving. As a result, there are limitations in setting the optimal rates of rotation and revolution relative to the finishing level and processing time.
Further, multiple processing objects, such as optical fiber connectors or ferrules 133, fixed on a support plate 131 must face in a direction perpendicular to the polishing disc 118 to obtain the desired convex rounded surface with the fiber at the top. However, since the support plate 131 is affixed to a support table A via a pressure welding member S, a vertical setting error due to the fit between the pressure welding member S and the support plate 131 and a fixing screw 136 inevitably occurs, causing the ferrule's angle of contact to become slanted.
As a result, the finished surface of the ferrule deviates from the ideal convex rounded surface with the fiber center at the top, and the connection of the connectors is greatly affected.
Accordingly, in order to resolve the above problems with the conventional polishing devise, the object of the present invention is to obtain a polishing machine which can independently set the rates of rotation and revolution of the polishing disc and to introduce a polishing mechanism which can make the polishing object come into contact with the polishing disc in a proper fashion.